Coating compositions containing coal tar pitch and an epoxy ether resin



United States Patent COATING'COMPOSITIONS CONTAINING COAL TAR PITCH AND AN EPGXY ETHER RESIN 'FretfWhittier and Raymond J. Lawn, Pittsburgh, 'Pa.,

assignors to Pittsburgh Coke '& Chemical Company, Pittsburgh, Pa., a corporation of Pennsylvania NuDrawing. 'Applica'tionDecember 28, 1954, Serial him-478,208

'14 Claims. (Cl. 26028) The present inventionrelatestofnovel coating compositions and, more particularly, to cold or air setting corrosion-resistant bituminous compositions which are especially adapted for application to steel and concrete surfaces, although not limited to such uses.

The present application is a continuation-in-part of application Serial No. 39 0,426,filed November 5, 1953,

now abandoned.

At the present time, the joints of pipe lines, for example, are generally coated in either of two ways, namely, by

'hand' brushing 'with'hot' coal tar coating, made up of bituminouspitch and inert fillers, such as-talc, silica or mica, or by application ofa thick bituminous cut-back coating. 'However, neither of the above methods is entirely satisfactory. Thus, for example, the use of hot 'bituminous coatings, or enamels, is expensive, because of :rapidly to give corrosion resistant and otherwise highly desirable sealingfilms.

Other objects will also be apparent from the description of the invention which follows.

Broadly stated,-the products of the invention comprise a glycidyl 'polyether resin (epoxy ethers),-as more fully described hereinafter, and coal tar pitch, with or without .finely divided inert fillers, such as talc, mica, silica, and -one or more aromatic hydrocarbon vehicles (solvents or diluents).

lln Bradley Patent No. 2,528,417, it has been proposed -to'use.a phenolic pitch with epoxy resins. Specifically, the ,pitch .employedin thepatent is a higher boiling aqueous alkali extract of cracked petroleum, the principal constituentsofwhich are higher boiling alkyl phenols. Bradley further ,points out that his pitch is miscible in all proportions with ethanol and isopropanol in contrast to asphalts and hydrocarbon pitches.

In contrast to the phenolic pitches of Bradley, the coal tar pitch employed-in the present invention is mainly hydrocarbon in nature and is practically insoluble in aqueousalkali, ethanol and isopropanol. Chemically, the pitch ofthe Bradley patent and the present coal tar pitch are non-analogous and it could not be predicted that coal tar pitch could be successfully employed with epoxy resins from the fact that phenolic pitches had been usedin the past with such resins.

The epoxy ethers or resins, suitable for use in the compositionsv of the invention, correspond with those described in vU. S. Patents Nos. 2,528,417, of October 31,

1950, and 2,500,449, of March 14, 1950, i. e., they contain along with ethereal oxygen, glycidyl groups in such quantity that the material has a 1,2-epoxy equivalency Patented Oct. 2, 1956 ice .2 in theaverage molecule, of greater than one. By the epoxy equivalency, reference is made to the averagenumber of 1,2-epoxy groups contained in the average molecule of'theeth'er.

A preferred group of epoxyethers for use in the' invention is prepared by reacting a dihydric'phenol'withepi- "chlorhydrin in alkaline solution. These products are of hydroxy benzophenone, 'bis (4- hydroxyphenylyljl ethane, -bis-(4-hydroxyphenyl)-1,l-isobutane, bis-(4-hydroxyphenyl) -2,2butane, bis- ('4-hydroxy-2-methylphenyl)-2,2-propane, bis-(hydroxy-Ztertiary butyl phenyl)- 2,2-propane, bis-(2-dihydroxynaphthyl) methane, lj5 dihydroxy naphthalene,'etc. The product may be represented by the formula:

wherein n is an integer, preferably from 1 to 7, and R represents the divalent hydrocarbon radical of the dihydric phenol. The preferred epoxy ethers for use in the invention are those having epoxy values'no les's'than 0:20 (Pyridinium Chloride Method and melting points no greater than -C. (Durrans Mercury Method). The preferred phenol is bis-phenol A.

Less preferably, there canbe'used 1,2-epoxy-containing polyethers of polyhydric alcohols, such aspolyglycidyl ethers thereof, like the diglycidyl ether of ethylene glycol, propylene glycol, trimethyleneglycol, diethylene glycol, triethylene glycol, glycerol, dipropylene glycol and the like. Other typical ethers of. this class include glycidyl ethers of polyhydric alcohols having a 1,2-epoxy equivalency. greater than one, such: as thepolyglycidyl ethers of glycol, diglycerol, erythritol, pentaglycerol, rnannitol, sorbitolpolyallyl alcohol, polyvinyl alcohol, and thelike.

In general, the glycidyl ether resin will havean-epoxy equivalency greater than-1 and usually less than 2L The epoxy equivalency may be defined as the number of epoxy groups per molecule in contrast to the epoxy value which is the number of epoxy groups in grams of the resin.

In addition to the coal tar pitch, epoxy ether resin-and, if desired, filler and vehicle, the products of the invention should also include'an agent'for rapid setting or curing of the coating. For this purpose, there may be used small amounts of poly-functional amines, such as ethylene 1 diamine, ethylene triamine, .diethylene triamine, benzyl dimethylamine, 3-dimethylaminopropylamine, 3-di- 1 ethylaminopropylamine, .tetra'ethylene"pentamine and the like. These agents, which apparently efiect cross linking in the epoxy resin, may be used in various amounts, although they usually are employed in the range of from 0.05 to 0.25 "part'p'er'part byweightofepoxy etherresin in conjunction with b'ituminouspitch'inert fillers and organic vehicles.

Since thepreferable epoxy resins may be set into a cured state simply by the additionthereto of the curing agent at ambient temperatures (10 to 60 C), thesetwo ingredients should be kept separated-until just before application of the composition to the surface to be coated, e. 2., metal or concrete surface or pipe linejoints.

Accordingly, the products'of the invention s'houl'dbe made up in the form of a two-component system, one

" pitch and, if desired, filler and vehicle, according to the invention, can be widely varied. Thus, compositions of the invention may comprise from to 50 parts epoxy ether resin and from 85 to 50 parts pitch based on 100 parts by weight of the total resin-pitch content. Satisfactory products may also be obtained using proportions outside the range recited above, e. g., up to 80% by weight of resin, although where, for example, substantially lower amounts of the preferable epoxy ether resins than those stated are used, the curing time is usually too long.

As indicated above, aromatic hydrocarbon vehicles, i. e., solvents or diluents, such as high flash naphtha, xylol, toluol, and the like, may be incorporated in the compositions of the invention in amounts sutficient to reduce the viscosity of the composition to a workable consistency. As will be appreciated, the aromatic hydrocarbon vehicle may be excluded if a workable viscosity is obtained without the same.

The invention is further illustrated, but not limited, by the following examples, wherein parts and percentages referred to are on a weight basis.

EXAMPLE I The following two component product was prepared by uniformly mixing the designated ingredients together:

Componenta Parts Epoxy ether resin from bis-phenol A and epichlorhydrin (melting point 9 C. and epoxy value 0.50) 90 Aromatic highflash naphtha 57 Coal tar pitch 94 Talc 47 Component b Diethylene-triamine (curing agent) 12 Components a and b were mixed together at the point of application and the resulting mixture brushed onto 1 steel pipe line joints at to 30 C. The mixture became set into a tough, corrosion-resistant, rubbery film within about twenty-four hours.

EXAMPLE II As in Example I, the following two component product was formed:

Component a Parts Epoxy ether resin from bis-phenol A and epichlorhydrin (melting point 30 C. and epoxy value Components a and b were admixed and the resulting mixture immediately applied to steel pipe line joints by brushing at a temperature of between 20 and 30 C. A

tough and otherwise highly desirable film was obtained.

by permitting the coating to stand at room temperature C.) for about twenty-four hours.

4 EXAMPLE III As in Example I, the following two component product was formed:

Component a Parts Epoxy ether resin from bis-phenol A and epichlorhydrin (liquid at 25 C. and an epoxy value 0.64) 50 Coal tar pitch 50 Aromatic solvent (xylene, benzene) 15 Component b Dicthylene triamin 7.5

EXAMPLE IV Component a Parts Epoxy resin from bis (4-hydroxyphenyl)-2,2-propane (melting point 25 C. and epoxy value 0.34)---- 50 Component b Diethylene tr V 3 Pitch V 35 Filler (inert mineral talc-clay) 15 Solvent (highflash naphtha) j 15 Components a and b were mixed together at the point of application and the resulting mixture brushed onto steel pipe line joints at 20 to 30 C. The mixture became set into a tough, corrosion resistant, rubbery film within about twenty-four hours.

It will be appreciated that various modificationsof the invention as described herein may be made without in any way deviating from the invention as defined in the appended claims.

We claim:

1. A cold setting bituminous composition comprising coal tar pitch substantially insoluble in alkali, ethanol, and isopropanol, an epoxy ether resin having a 1,2-e'poxy equivalency greater than 1 and a curing agent for said epoxy ether resin, wherein said epoxyether resin is between 15% and of the mixture of epoxy ether resin prising coal tar pitch substantially insoluble in alkali,

ethanol, and isopropanol, a glycidyl polyether of a dihydric phenol having a 1,2-epoxy equivalencyigreater than 1 and a curing agent for said glycidyl polyether, wherein said glycidyl polyether is between 15% and 80% of the mixture of glycidyl polyether and said coal tar pitch.

3. The coating composition of claim 2, wherein the epoxy ether resin has an epoxy value no less than 0.20 and a melting point no greater than 80 C.

4. The coating composition of claim 2, including a filler. e

5. The coating composition of claim 2, including an aromatic hydrocarbon vehicle.

6. The coating composition of claim 2, including an aromatic hydrocarbon vehicle and a filler.

7. The coating composition of claim 2, wherein the curing agent is an amine having a plurality of of amino groups.

8. The composition of claim 2, comprising from 15 to 50 parts epoxy ether resin and having an epoxy value no less than 0.20 and a melting point no greater than 80 C., and to 50 parts of said coal tar pitch'based on '100 parts by weight of the resin-pitch content; from 0.05 to 0.25 part of said curing agent per each part by weight of epoxy ether resin; sufiicient solvent to give the desired consistency to said composition.

9. A steel base coated with a tough, corrosion resistant film obtained by permitting the composition of claim 2 to set thereon.

10. A concrete base coated with a tough, corrosion resistant film obtained by permitting the composition of claim 2 to set thereon.

11. A composition according to claim 2 wherein the glycidyl polyether is a glycidyl polyether of bis-(4-hydroxyphenyl) 2,2-prop ane.

12. The coating composition of claim 11 wherein the glycidyl polyether has an epoxy value no less than 0.20 and a melting point no greater than 80 C.

13. The composition of claim 12 comprising 15 to parts of the glycidyl polyether, to 50 parts of the coal tar pitch, from 0.05 to 0.25 part of curing agent per part by weight of polyether and sufficient solvent to give a workable viscosity to the composition.

14. The composition of claim 11 wherein the curing agent is an amine having a plurality of amino groups.

References Cited in the file of this patent UNITED STATES PATENTS 2,528,417 Bradley Oct. 31, 1950 

1. A COLD SETTING BITUMINOUS COMPOSITION COMPRISING COAL TAR PITCH SUBSTANTIALLY INSOLUBLE IN ALKALI, ETHANOL, AND ISOPROPANOL, EPOXY ETHER RESIN HAVING A 1,2-EPOXY EQUIVALENCY GREATER THAN 1 AND A CURING AGENT FOR SAID EPOXY ETHER RESIN, WHEREIN SAID EPOXY ETHER RESIN IS BETWEEN 15% AND 80% OF THE MIXTURE OF EPOXY EHTER RESIN AND SAID COAT TAR PITCH. 